Most of the time, we naturally benefit from the semantic context to easily produce and perceive language, but semantic facilitation in speech production remains poorly investigated and thus poorly understood. So far, research on word production has actually focused on semantic interference, i.e., situations in which the semantic context perturbs the word production process, causing a slowdown and/or speech errors. In the present work, both semantic facilitation and interference are investigated in two influential picture naming paradigms (the picture-word paradigm and the blocked-cyclic naming paradigm), by means of electro-encephalography (in healthy speakers) and lesion-to-symptom mapping (in aphasic speakers). The underlying processes of semantic facilitation and interference are discussed in the light of current psycholinguistic and neuroanatomical models of word production.